Strain Components

EPSX X Normal strain
EPSY Y Normal strain
EPSZ Z Normal strain
GMXY Shear strain in Y direction on YZ plane
GMXZ Shear strain in Z direction on YZ plane
GMYZ Shear strain in Z direction on XZ plane
ESTRN Equivalent strain
SEDENS Strain energy density
ENERGY Total strain energy
E1 Normal strain in the first principal direction
E2 Normal strain in the second principal direction
E3 Normal strain in the third principal direction

Equivalent strain (ESTRN)

ESTRN=2 [(ε1+ε2)/3](1/2)

Where:

ε1 = 0.5 [(EPSX - ε*)2 + (EPSY - ε*)2 + (EPSZ - ε*)2]

ε2 = [(GMXY)2 + (GMXZ)2 + (GMYZ)2] / 4

ε* = (EPSX + EPSY + EPSZ) / 3

ENERGY

Total Strain Energy = ∑ [( SX * EPSX + SY * EPSY + SZ * EPSZ + TXY * GMXY + TXZ * GMXZ + TYZ * GMYZ) * Vol(i) * W(i) /2] for i=1 , N int

N int are the integration points (or Gaussian points), W(i) is the weighted constant at integration point i, and

( SX = X normal stress, SY = Y normal stress, SZ = Z normal stress, TXY = Shear in Y direction on YZ plane, TXZ = Shear in Z direction on YZ plane, TYZ = Shear in Z direction on XZ plane )

Strain energy density (SEDENS)

SEDENS = Total Strain Energy / Volume , Volume = ∑ [ Vol(i) * W(i)] , i =1, N int.